The proposed studies are designed to identify, molecularly clone and characterize cellular genes which comprise and/or regulate the biochemical pathways essential for the process of malignant transformation. The specific aims of the present proposal include the following: (1) Revertants resulting from mutations in different transformation effector and suppressor genes will be derived from: (a) populations of v-fos transformed fibroblasts treated with a variety of mutagens; (b) from populations of cell transformed with a variety of different oncogenes. (2) The transformation effector genes present in normal cells will be identified by their ability to induce retransformation of revertant cells in DNA mediated gene transfer experiments. (3) Dominant transformation suppressing genes will be identified in revertant cells isolated from populations of tumor cells transfected with genomic DNA or cDNA's derived from normal human cells. (4) The transfected transformation effector and suppressor genes will be molecularly cloned from genomic libraries or cDNA libraries prepared from the recipient cells, and subjected to nucleotide sequence analysis. (5) Antisera to each of the cloned effector and suppressor gene products will be developed using synthetic peptides or proteins partially purified from bacteria expressing the cDNA clones. These antisera will be used to study the biochemical properties of their corresponding proteins, their intracellular localization, as well as the relative expression and processing in normal versus transformed cells.